Occupants in a car can enjoy audio programs from various types of audio sources such as a CD player, an analog and digital radio tuner, an MP3 player and the like. Conventionally, such an entertainment system is controlled by a head unit that is typically installed in a dashboard and a desired audio source is selected with buttons provided on the head unit. The buttons control audio switches that connect the desired audio source to an amplifier-loudspeaker system. In general, simple audio switches may generate switching spikes, which can cause the known problem of switching noise or “pops”, or may cut off parts of the signal. Since highest quality stereo audio is becoming increasingly popular in car audio systems, switching noise and signal degeneration are unacceptable. Therefore, there exists a need for non-obtrusive switching between audio sources.